In general, future-generation communication systems are under development to provide high-speed large-volume data transmission and reception services to mobile stations. A major example of them is Institute of Electrical and Electronics Engineers (IEEE) 802.16e.
With reference to FIG. 1, the configuration of an IEEE 802.16e communication system will be described.
FIG. 1 illustrates the configuration of a typical IEEE 802.16e communication system.
Referring to FIG. 1, the IEEE 802.16e communication system is multi-cellular. Thus, it includes cells 100 and 150, a base station (BS) 110 that covers the cell 100, a base station 140 that covers the cell 150, and a plurality of receivers 111, 113, 130, 151 and 153.
In an Orthogonal Frequency Division Multiple Access (OFDMA) communication system such as the IEEE 802.16e communication system, a base station requires uplink Channel Quality Information (CQI) of each receiver (MS) in order to allocate uplink resources. For this purpose, the base station can allocate dedicated uplink resources to receivers so that they transmit reference signals or pilot signals to the base station. The following description is made on the assumption that each mobile station transmits a pilot signal and the base station acquires the uplink CQI of the receiver by estimating the pilot signal received from the receiver.
If the IEEE 802.16e communication system operates in Time Division Duplex (TDD), it can be considered that an uplink CQI is equal to a downlink CQI. Even in Frequency Division Duplex (FDD), the downlink and uplink CQIs can be transmitted simultaneously by transmitting an analog downlink CQI value and a pilot signal at the same time. In the case where the IEEE 802.16e communication system does not use TDD, the base station acquires the uplink CQI of each receiver as follows.
In the IEEE 802.16e communication system, an uplink frame includes a sounding zone in which each receiver transmits a sounding signal on subcarriers. The sounding signal is a pilot signal by which the base station can acquire the uplink CQI of the receiver. For convenience sake, the terms “sounding signal” and “pilot signal” are interchangeably used in the same meaning.
Only upon request of the base station, the receiver transmits the sounding signal using allocated subcarriers and time resources in the sounding zone. The sounding zone has uplink resources common to all receivers within the base station. Under the control of the base station, the receivers share the subcarriers of the sounding zone.
As described above, to estimate the uplink CQIs of the receivers, the base station should transmit to the receivers uplink resource allocation information indicating frequency resources and time resources in which they will transmit their sounding signals. The uplink resource allocation information includes the following:                (1) The number of allocated sound pilots;        (2) The time-frequency positions of the sounding pilots; and        (3) A sounding pilot allocation period.        
To acquire the uplink CQIs of the receivers, the base station should transmit the above complex information to the receivers, for uplink resource allocation to them. Accordingly, reduction of the uplink resource allocation information associated with the uplink CQI acquisition is very significant in terms of overall system overhead.